Retinitis pigmentosa is regarded as untreatable; nothing can be done to halt the slow progression of the disease or to restore lost vision. However, in China, a daily intramuscular injection of a herb extract has recently been used to treat retinitis pigmentosa. This rare fungal herb, Ganoderma lucidum, has been used for thousands of years as a nontoxic and broadly effective energizing and strengthening agent. Treatment of retinitis pigmentosa with the herb has brought striking improvements in visual field, visual acuity and electroretinogram. The mechanism of action is unknown. This proposal involves pilot pharmacologic studies of the effect of Ganoderma lucidum on hereditary retinal degeneration in mice. Crude material and a purified polysaccharide component of Ganoderma lucidum will be tested for their ability to retard retinal degeneration in young C3H mice. Accumulation of cyclic GMP in the photoreceptors, phosphodiesterase enzyme activity, and morphological characteristics will be used as test criteria. This study will explore the feasibility of performing more extensive laboratory investigations. Favorable results with this herb may lead to a breakthrough in the medical treatment of retinitis pigmentosa or other retinal degenerations.